Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income, Basic	$ 45,475	$ 57,583	$ 95,522	$ 103,890
Net income, Diluted	$ 45,475	$ 57,583	$ 95,522	$ 103,890
Weighted average common shares outstanding, Basic	118,164	117,401	117,974	117,318
Weighted average common shares outstanding, Basic	118,164	117,401	117,974	117,318
Weighted average shares and assumed conversions	118,585	118,009	118,423	117,889
BASIC EARNINGS PER SHARE	$ 0.38	$ 0.49	$ 0.81	$ 0.89
DILUTED EARNINGS PER SHARE	$ 0.38	$ 0.49	$ 0.81	$ 0.88
Stock options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	377	514	398	473
Restricted stock based awards
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities	44	94	51	98